// use std::HashMap;
use std::collections::HashMap;
fn main() {
    println!("Hello, world!");

    let a = "a";
    let b = "b";

    let mut hm: HashMap<&str, u32> = HashMap::new();
    if !hm.contains_key(a) {
        hm.insert(a, 1);
    }

    if !hm.contains_key(b) {
        hm.insert(b, 2);
    }

    if !hm.contains_key(a) {
        hm.insert(a, 3);
    }

    dbg!(hm);
}
